Management of hierarchically configured storage

ABSTRACT

In a computer system having a storage system in which storage units are hierarchically configured, a management method for accurately grasping the capacity available to the computer is disclosed. 
     In a computer system in which a management computer manages the capacities of storage units for storing data used by the computer, the management method is typically realized by a storage management system comprising a group of first-level storage units each containing volumes for storing data used by the computer, a group of second-level storage units each of which is hierarchically linked to, and physically connected through a communication path to, one of the first-level storage units and contains volumes for storing data used by the computer, a means for collecting volume information from the first-level and the second-level storage units, a means for collecting inter-volume hierarchy information, and a means for calculating the total effective capacity to the computer based on the volume information and the inter-volume information thus collected.

This application is a continuation of U.S. patent application Ser. No.10/786,108, filed Feb. 26, 2004 now U.S. Pat. No. 7,089,359.

BACKGROUND OF THE INVENTION

The present invention relates to a storage management method, and morespecifically to a method for managing the capacities of volumescontained in storage units in a computer system having a hierarchicallyarranged group of storage units.

DESCRIPTION OF THE PRIOR ART

In a large-scale storage system such as a disk array system, eachstorage unit is divided into a number of virtual storage areas calledvolumes. Stored in each such volume are programs to be executed by thecomputer to which the storage unit is connected and their associateddata that is necessary for executing them. The information concerningthe volumes such as the number of volumes allocated to each storage unitand the capacity of each volume (typically expressed in bytes) can beobtained through the management interface to which the storage units areconnected.

Another system according to the prior art allows a volume with a desiredcapacity to be created in a storage unit through a management interface.For example, the Storage Networking Industry Association (SNIA;http://www.snia.org) is working on the establishment of a storagemanagement interface based on the Common Information Model (CIM) andWeb-Based Enterprise Management (WBEM), the standardization of which isbeing promoted by the Distributed Management Taskforce (DMTF). Morespecifically, SNIA has published the Storage Management InitiativeSpecification (SMI-S), which sets forth a set of specifications for howto check the capacity of a given volume in a given storage unit and forhow to create a volume in a given storage unit.

Furthermore, Publication of Japanese translation of a PCT applicationHeisei 10-508967 (WO97/09676) (reference #1) discloses a storage systemwhich allows online data transfer between two storage units that aresituated in different levels of storage hierarchy.

[Reference #1]

Publication of Japanese translation of a PCT application Heisei10-508967 (WO97/09676)

[Reference #2]

SMI-S Specification PUBLIC REVIEW DRAFT (pp. 103–114, pp. 146–182)[online], Storage Networking Industry Association (SNIA), Apr. 15, 2003(accessed on Jun. 4, 2003) (Internet URL:http://www.snia.org/smi/tech_activities/smi_spec_pr/spec/SMIS_(—)1615a.pdf)

SUMMARY OF THE INVENTION

The invention disclosed in Publication of Japanese translation of a PCTapplication Heisei 10-508967, assuming that a first-level storage unitand a second-level storage unit belonging to different levels ofhierarchy support a management interface of the type described above,allows a management computer having the same management interface todetect, and communicate with, both of these storage units through anetwork. For example, by interrogating any storage unit, the managementcomputer can obtain the number of volumes contained in it or informationon the capacities of the volumes contained in it.

In a configuration where a second-level storage unit is hierarchicallyconnected to a first-level storage unit, data migration involves makinga volume in the second-level storage unit available for use as a volumein the first-level storage unit. The management computer then needs torealize that certain volumes in the second-level storage unit are infact used as volumes belonging to the first-level storage unit and alsoto know the total effective capacity in the system.

It is an object of the present invention to provide, in a storage systemin which storage units are hierarchically configured into multiplelevels, a storage management system and a storage management method forrealizing the hierarchical structure of the storage units and accuratelygrasping and displaying the total available storage capacity.

In a computer system comprising a computer, a plurality of storage unitseach containing one or more volumes for storing data used by thecomputer, and a management computer for managing the status of thestorage units, the invention relates to a storage management systemcomprising one or more first-level storage units each containing one ormore volumes for storing data used by the computer, one or moresecond-level storage units each of which is connected to one of thefirst-level storage units through a communication path in a hierarchicalconfiguration and contains one or more volumes for storing data used bythe computer, means for collecting from the first and the second-levelstorage units volume information on the volumes contained in them, meansfor collecting inter-volume hierarchy information on the hierarchicalrelationships between volumes contained in the first storage units andvolumes contained in the second-level storage units, and means forcalculating the total effective capacity to the computer based on thevolume information and the inter-volume hierarchy information thuscollected.

In a preferred embodiment of the invention, the first and thesecond-level storage units each contain one or more virtual storageareas called volumes. The means for collecting volume information, themeans for collecting inter-volume hierarchy information, and the meansfor calculating the total effective capacity are all provided by eachprogram, which is executed in the management computer.

In the preferred embodiment, the information on the hierarchicalrelationships between the volumes contained in a first-level storageunit and the volumes contained in a second-level storage unit is held inthe first-level storage unit, which is the higher in the hierarchy. Thisis accomplished, for example, by providing each first-level storage unitwith a program for processing hierarchy information requests, whichcollects information from the storage units connected to it.

The management computer is equipped with a display unit (hereinaftersimply called “display”) to display the storage capacities of thevolumes contained in each storage unit and the inter-volume hierarchicalrelationships. In the preferred embodiment, the display has at least twodisplay sections: one for displaying the information on the volumescontained in the second-level storage units that are used by thefirst-level storage units, and the other for displaying the informationon the other volumes.

The process of managing the storage capacities of volumes using themanagement computer according to the preferred embodiment of theinvention comprises a step for allocating a volume in a first-levelstorage unit for storing data used by the computer, a step forestablishing a hierarchical relationship between a first-level storageunit and a second-level storage unit so that a volume is shared betweenthe two, a step for collecting information on the volumes contained inthe first-level storage units, a step for collecting information on thevolumes contained in the second-level storage units, a step forcollecting information on the hierarchical relationships between thevolumes in the first-level storage units and those in the second-levelstorage units, and a step for calculating the total effective capacityin the computer system based on the information on the volumes and theinformation on the hierarchical relationships thus collected. Thisprocess is carried out by a program for managing the storage capacitiesof the volumes running on the management computer.

The invention makes it possible to accurately grasp, in a computersystem having a hierarchically arranged group of storage units, thestorage capacity available to the computer. Furthermore, it displays onthe display of the management computer information on the realcapacities of the volumes considering the hierarchical relationshipsbetween them, thereby providing the user with accurate information onthe capacities of the volumes that are hierarchically configured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the general configuration of a computer systemaccording to a preferred embodiment of the invention.

FIG. 2 shows the format of volume information according to a preferredembodiment.

FIG. 3 shows the format of information on the hierarchical relationshipaccording to a preferred embodiment.

FIG. 4 shows an example of a computer system according to a preferredembodiment.

FIG. 5 shows the format of the identifier according to a preferredembodiment.

FIG. 6 shows the format of the consolidated information table accordingto a preferred embodiment.

FIG. 7 illustrates the process flow of creating the consolidatedinformation table in a management computer 501 according to a preferredembodiment.

FIG. 8 illustrates the flow of process carried out in the storage unit(e.g., 201) according to a preferred embodiment.

FIG. 9 shows an example of the display according to a preferredembodiment.

FIG. 10 shows the format of volume information according to anotherembodiment of the invention.

FIG. 11 shows an example of the display according to another embodiment.

FIG. 12 shows an example of the display according to still anotherembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will now be described by way ofexample and with reference to the accompanying drawings.

FIG. 1 shows a computer system comprising four computers 301 through304, a first-level storage unit 201, and two second-level storage units101 and 102, and a management computer 501. The first-level storage unit201 and the second-level storage units 101 and 102 each contain at leastone virtual storage area called a volume. The second-level storage units201 and 202 are connected to the first-level storage unit 201 through acommunication path in a hierarchical configuration. It should be notedthat more than one volume may be allocated within one storage unit orone volume may span more than one storage unit.

The computer 301 is connected to a volume 211, the communication withwhich is controlled by the first-level storage unit 201. Stored in thevolume 211 are programs used by the computer 301, their input data, andtheir output data. Similarly, the computer 302 is connected to a volume212, the communication with which is controlled by the first-levelstorage unit 201. Further, the volume 212 is connected to a volume 111,the communication with which is controlled by the second-level storageunit 101. The volume 212 and the volume 111 are configuredhierarchically and each can hold data.

The computer 303 is connected to a volume 213, the communication withwhich is controlled by the first-level storage unit 201. The volume 213is connected to a volume 161 situated in the second-level storage unit102. The volume 213 cannot hold data; instead, the data for the volume213 is actually held in the volume 161. When the computer 303 sends awrite request directed to the volume 213, the first-level storage unit201 asks the computer 303 to send the write data and, upon receiving it,sends a write request to the volume 161. The second-level storage unit102 then stores the data into the volume 161. When the computer 303sends a read request directed to the volume 213, the first-level storageunit 201 passes it to the volume 161. It then obtains the read datathrough the second-level storage unit 102 to which the volume 161belongs and passes it to the computer 303. Alternatively, it can be soarranged that the volume 213 represents the volume 161 either for reador for write operation only. In effect, the volume 213 does not exist inthe first-level storage unit 201 but instead acts just as a phantomarea, and therefore is shown in dotted lines in the diagram. Thus, thevolume 161 situated in the second-level storage unit 102 appears to thecomputer 303 as if it is situated in the first-level storage unit 102.

The computer 304 is connected to the volume 162, the communication withwhich is controlled by the second-level storage unit 102. Stored in thevolume 162 are programs used by the computer 304, their input data, andtheir output data.

The storage units 201, 101, and 102 are each equipped with a managementinterface unit (I/F) 220, 120, and 170, respectively, for connection tothe management computer 501.

While the configuration and operation of the management computer 501will be described in detail later with reference to FIG. 4, an overviewwill be presented here.

In a computer system comprising one or more computers and ahierarchically arranged group of storage units, the management computer501 is designed to grasp the storage capacity actually available to eachcomputer and for that purpose is equipped with a volume informationcollecting program 520, a hierarchy information collecting program 540,an effective capacity calculating program 550, and a display 590 fordisplaying the effective capacities calculated by the effective capacitycalculating program 550 for the system administrator.

The volume information collecting program 520 issues volume informationrequests to the storage units 201, 101, and 102 and obtains information(248, 148, and 198, respectively) on the number of volumes and thecapacity of each volume in each storage unit. FIG. 2 shows examples ofthe volume information.

The hierarchy information collecting program 540 obtains hierarchyinformation 245 held by the first-level storage unit 201. The effectivecapacity calculating program 550 calculates, based on the volumeinformation and the hierarchy information thus collected, the effectivecapacities actually available to the computers 301 through 304.

FIG. 3 shows an example of the format of the hierarchy informationobtained through the hierarchy information 245. Each volume is assignedan identifier. For example, the identifier of the upper-level(first-level) volume 212, “ABC.XX200.0123.212,” is associated with theidentifier of the lower-level (second-level) volume 111,“DEF.YY100.0456.111.” This relationship is held in an internal memory(not indicated in the diagram) of the first-level storage unit 201. Whenthere is a change to the hierarchical relationship between a volume in afirst-level storage unit and a volume in a second-level storage unit,this hierarchy information is revised accordingly.

Assuming that the volumes 111, 161, 162, 211, 212, and 213 each have astorage capacity of 100 G bytes (hereinafter abbreviated to “GB”), FIG.2 shows the volume information collected by the management computer 501.(A) represents the volume information 248, which lists all the volumesallocated to the storage unit 201 and which indicates that the totalnumber of volumes is 3 and each volume has a capacity of 100 GB.Similarly, (B) represents the volume information 148 corresponding tothe storage unit 101, and (C) represents the volume information 198corresponding to the storage unit 102.

If the management computer 501 were not to recognize the hierarchicalrelationships between volumes in the first-level storage units and thesecond-level storage units, then it would assume, by simply adding upthe capacity of each volume, that a total of 600 GB were available inthis computer system. The preferred embodiment of the inventiondescribed here, however, allows the management computer to calculate thetotal available capacity considering the hierarchical relationships,thereby preventing such misjudgments. Thus, the management computer 501,realizing that the volume 111 is subordinate to the volume 212 and thevolume 161 is subordinate to the volume 213, making the number of realvolumes four, calculates the total effective storage capacity to be 400GB.

FIG. 4 shows an example of the configuration of a computer systemaccording to the preferred embodiment being described.

The computers 301 through 303 are connected to the storage unit 201through a fibre channel switch (hereinafter abbreviated to “FC switch”)401. Each of the computers 301 through 304 comprises a CPU 310, a memory320, and a fibre channel interface unit (hereinafter abbreviated to “FCinterface unit”) 330. The FC interface unit 330 handles the interfaceoperation between the computer and the FC switch. The memory 320 storesprograms to be executed by the CPU 310, their input data, and theiroutput data.

The storage unit 201 is connected through three FC interface units 230inside it to the FC switch 401. The storage unit 201 includes aread/write request processing module 232, which receives read/writerequests from the computers through the FC interface units 230, readsthe requested data from the specified volumes and sends it to thecomputers, or writes the data sent from the computers to the specifiedvolumes.

The storage unit 201 contains volumes 211 and 212, each having acapacity of 100 GB, for storing data to be used by the computers. Thestorage unit 201 further contains two FC interface units 235 forconnection to other storage units 101 and 102, which serve aslower-level or subordinate storage units. The storage unit 201 alsocontains a data synchronization control module 238 inserted between thevolume 212 and the FC interface unit 235 to establish datasynchronization between the volume 212 and the volume 111 which isconnected to the volume 212 through the FC interface unit 235. The datasynchronization module 238 ensures that data consistency is maintainedall the time between the two volumes (in this example, the volume 111and the volume 212).

The storage unit 201 is also connected to two storage units 101 and 102through an FC switch 402. Each of the storage units 101 and 102comprises an FC interface unit 130 for connection to the FC switch 402and a read/write request processing module 132. Further, the storageunit 101 comprises the volume 111 which stores data to be used by thestorage unit 201. The storage unit 102 further comprises a volume 161that stores data to be used by the storage unit 201 and a volume 162that stores data to be used by the computer 304.

Whereas in the example described here a fibre channel network is assumedfor connection between storage units and computers as well as betweenstorage units, different types of network may be used instead, in whichcase appropriate devices or units need to be installed in place of FCswitches and FC interface units. The FC switch 401 and the FC switch 402may be used separately or may be connected in a cascade configuration.

A description of the management computer 501 and the managementinterface unit is now in order.

In the computer system depicted in FIG. 4, a management interface unit410 is provided for grasping the configurations and capacities of thevolumes. The storage units 101, 102, and 201 are each equipped with amanagement interface unit 120, 170, and 220, a CPU 121, 171, and 221,and a memory 123, 173, and 223, respectively. The memories 123, 173, and223 each store programs to be executed by the CPU, data received throughthe management interface unit, and data to be sent through themanagement interface unit.

More specifically, the memory 223 in the storage unit 201 stores avolume information request processing program 225 for processing volumeinformation requests from the management computer 501, a hierarchyinformation request processing program 226 for processing hierarchyinformation requests, and an identifier format inquiring program 227 forobtaining an identifier format from an identifier management computer601 (to be described later).

The memories 123 and 173, which are situated in the storage units 101and 102, each store a volume information request processing program 125and 175 for processing volume information requests and an identifierformat inquiring program 127 and 177, respectively, for obtaining anidentifier format from the identifier management computer 601. Thestorage units 101 and 102 are connected through a management network 410to the management computer 501.

The management computer 501 comprises a network interface unit 510 forconnection to the management network 410, a CPU 511 for performinginformation processing inside it, a display 590 for displaying theresults of the processing performed by the CPU 511, a memory 513 forstoring programs to be executed on the CPU 511, data received or to besent through the network interface unit 510, and data to be displayed onthe display 590, and an input device 592 for receiving instructions fromthe administrator. Stored in the memory 513 are a volume informationcollecting program 520 for issuing volume information requests tostorage units, a hierarchy information collecting program 540 forissuing hierarchy information requests, an effective capacitycalculating program 550 for calculating the effective capacity, and anidentifier format collecting program 527 for obtaining an identifierformat from the identifier management computer 601.

The above-mentioned programs are originally stored in a nonvolatilestorage medium such as a magnetic disk provided inside the managementcomputer 501 and are loaded into the memory 513 for execution each timethe management computer is started up. Other types of nonvolatilestorage medium such as a CD-ROM and a floppy disk may also be used.Whereas in the example described here these programs are loaded from anonvolatile storage medium held inside the management computer, they mayalso be loaded from an outside source through a network.

Next, the function and operation of the identifier management computer601 will be described.

The computer system further comprises, in addition to a number ofstorage units, an identifier management computer 601. Each storage unithas an identifier. The identifiers of storage units, however, do nothave a standardized format. Each storage unit manufacturer has its ownidentifier format. The identifier management computer 601 introduces astandardized identifier format, thereby registering and managing all thestorage units in the system using a standard format.

It should be noted that if all the storage units have a standardizedidentifier format, there is no need for an identifier managementcomputer.

The identifier management computer 601 comprises a network interfaceunit 610 for connecting to the management network 410, a CPU 611 forperforming information processing, and a memory 613 for storing programsto be executed by the CPU 611, data received or to be sent through thenetwork interface unit 610, and identifier formats, which are organizedand held in an identifier format table 650. Further, the memory 613stores an identifier format request processing program 620 forprocessing identifier format requests sent from the storage unit 201,101, or 102 (hereinafter abbreviated to “201, etc.”) or the managementcomputer 501.

When the identifier management computer 601 receives a request (inquiry)for the identifier format from an identifier format inquiring program227, 127, 177, or 527 (hereinafter abbreviated to “227, etc.”) residingin the storage unit 201, 102, or 102 or the management computer 501, theidentifier format request processing program 620 returns the identifierformat taken from the identifier format table 650 shown in FIG. 5. Theidentifier format specified by the identifier management computer 601sets forth the organization of the characters and fields making up theidentifier that must be followed by all the storage units in thecomputer system and the volumes held in them. As shown in FIG. 5, theidentifier format 650 comprises a string of characters, which is dividedinto several fields by delimiters 659 (dot “.”). More specifically, itcomprises a vendor name 651, a model name 652, a manufacturing number653, and a volume number 654. As the volume number 654, any of thenumbers in the blocks shown in FIG. 1 or FIG. 4 may be used, forexample, “ABC.XX200.0123.211.” If the identifier format is notstandardized, it would be difficult to grasp the total availablecapacity in the computer system, since the volume information and thehierarchy information obtained from different storage units cannot becompared with each other. Therefore, if the identifier format is notstandardized, it would be necessary to equip the management computer 501with a format conversion program that converts the formats of theidentifiers of the volume information and the hierarchy informationbetween different storage units.

The storage unit 201, etc. executes, each time it is started up, theidentifier format inquiring program 227, etc. and sends a request forthe identifier format to the identifier management computer 601. Inresponse, the identifier management computer 601 sends the identifierformat 650 to the storage unit 201, etc. The storage unit 201, etc.saves this identifier format 650 in its internal memory, and later whenrequested, composes volume information and hierarchy information inaccordance with it.

The management computer 501 executes, each time it is started up, theidentifier format inquiring program 527 and sends a request for theidentifier format to the identifier management computer 601. Inresponse, the identifier management computer 601 sends the identifierformat 650 to the management computer 501. The management computer 501saves this identifier format 650 in its internal memory and later usesit when reading the volume information or hierarchy information sentfrom the storage unit 201, etc. In this manner, matching in identifierformat can be maintained between the storage units 201, etc. and themanagement computer 501.

Now, the way the management computer 501 grasps the capacities of thevolumes held in the hierarchically configured group of storage unitswill be described with reference to FIGS. 7 and 8.

When started up, when requested through the input device 592, or whennotified by the storage unit 201, etc. of a change to the configuration,the management computer 501 initiates the process of grasping thestorage capacities.

First, the CPU 511 in the management computer 501 executes the volumeinformation collecting program 520 and issues a volume informationrequest to every storage unit connected to it (1101).

In the storage unit 201, 101, or 102, the CPU 221, 121, or 171 receivesthis request, recognizes the type of the request (1201), executes thevolume information request processing program 225, 125, or 175, consultsthe identifier format table 650 stored in the memory 223, 123, or 173(1203), prepares the requested volume information in the memory (1205),and finally sends it to the management computer 501 (1207).

The management computer 501 thus collects the volume information 248,148, and 198 shown in FIG. 2 from the storage units 201, 101, and 102,respectively (1103, 1105). In this case, although the storage unit 201has only two volumes 211 and 212, it responds to the request from themanagement computer 501 as if it also owns the volumes that are notcontained in it but that are connected to it through the FC interfaceunit 235.

Next, the CPU 511 in the management computer 501 executes the hierarchyinformation collecting program 540 and sends a hierarchy informationrequest to every storage unit connected to it (1107). In the storageunit, the CPU receives this request, recognizes the type of the request(1211), executes the hierarchy information request processing program,consults the identifier format table 650 stored in the memory (1215),prepares the hierarchy information in the memory (1217), and finallysends it to the management computer 501 (1219).

Since the storage unit 201 has the hierarchy information requestprocessing program 226 (1213), it can process this request properly.Thus, the management computer receives the hierarchy information 245shown in FIG. 3 (1109, 1111). On the other hand, the storage units 101and 102, which do not have the hierarchy information request processingprogram 226 (1213), their CPUs 121 and 171 send an “error” response(1299).

The management computer 501 then composes a consolidated informationtable 570 shown in FIG. 6 based on the volume information and thehierarchy information thus collected, and stores it in its memory 513.The consolidated information table 570 consists of an upper-volumecolumn 571 holding information on the higher-level volumes and alower-volume column 572 holding information on the lower-level volumes.

The algorithm for composing the consolidated information table 570 is asfollows.

First, the CPU 511 of the management computer 501 fetches the hierarchyinformation, and for each pair of volumes having a hierarchicalrelationship, registers their identifiers under their respective columnsin the same row (1113). Further, in the icon number field of the column571 of the same row, it puts “901,” which means an icon indicating thatthe volume has a subordinate volume connected to it (1114); in the iconfield of the column 572 of the same row, it puts “902,” which means thatthe volume is subordinate to the upper-level volume (1114).

Next, the CPU 511 fetches the volume information and checks it row byrow (1115). If the identifier corresponding to the selected row isalready registered (1117), then it registers the capacity in the fieldnext to the registered identifier (1121); otherwise (1117), it registersunder the column 571 for a new row, the identifier, capacity, and iconnumber, which in this case is “903,” meaning that it does not have anysubordinate volume (1119).

The CPU 511 repeats the above process for all the volumes whoseinformation has been obtained and for all the rows of the volumeinformation table (1123, 1125, 1126, and 1127). If more than one pieceof hierarchy information has been obtained, it will be reflected on theconsolidated information table 570. FIG. 6 shows an example of theconsolidated information table 570 which is composed of the volumeinformation shown in FIG. 2 and the hierarchy information shown in FIG.3. The total effective capacity to the computers in the system cantherefore be calculated by adding up the values in the capacity columncorresponding to upper-level volumes, which is 400 GB in this example(573).

The process of displaying the calculated capacity is now describedbelow, with reference to FIG. 9.

On the display 590 in the management computer 501, volume informationand hierarchical information are displayed as shown in FIG. 9. Thescreen 700 is divided into three display sections 701 through 703. Inthe display section 701, the information in the upper-volume column 571of the consolidated information table 570 is displayed. In the displaysection 702, the information in the lower-volume column 572 of theconsolidated information table 570 is displayed. The hierarchicalrelationships are indicated by icons corresponding to the icon numbersregistered in the icon number column (“901” through “903” in FIG. 6). Inthe display sections 701 and 702, the information displayed consists of,from left to right, the icon, the identifier, and the storage capacity.The display section 703 indicates the total effective capacity to thecomputers in the computer system. Use of characteristic icons withvisually distinct figures and colors allows the system administrator toeasily grasp on this screen the status of the volumes in the system at aglance.

To facilitate the viewing of volume and hierarchy information in asystem having a large number of volumes, each display section may beprovided with a scrolling feature.

By clicking the icon for a volume in the display section 701, it ispossible to check whether there exists a volume hierarchically linkedwith that volume and, if yes, to locate the hierarchically linkedvolume. The CPU 511 consults the consolidated information table 570 and,if it finds a valid identifier registered in the corresponding row underthe lower-volume column 572, highlights the corresponding entry in thedisplay section 702, for example, by changing the color of the icon orthe background of the identifier or framing the identifier. Similarly,when the icon for a volume in the display section 702 is clicked, theCPU 511 consults the consolidated information table 570 and, if it findsa valid identifier registered in the corresponding row under theupper-volume column 571, highlights the corresponding entry in thedisplay section 701.

The present embodiment thus makes it possible, in a computer system inwhich volumes are hierarchically configured, to grasp the totaleffective capacity to a computer. Further, by dividing the screen on thedisplay into two sections, i.e., one display section 701 for displayinginformation on the volumes used by the first-level storage unit 201 andthe other display section 702 for displaying information on the othervolumes, providing icons to represent the rank in hierarchy, andhighlighting hierarchical relationships between pairs of volumesspanning the two display sections, it allows the system administrator toeasily grasp the hierarchical relationships between volumes and thetotal effective capacity even when there exist hierarchicalrelationships between volumes.

Next, another preferred embodiment of the invention will be describedwith reference to diagrams.

This embodiment uses the same system configuration shown in FIG. 4 butuses formats of volume information and hierarchy information, as well asthe display format on the display 590, different from those in theprevious embodiment described so far.

The volume information has the format shown in FIG. 10. In response to avolume information request issued by the management computer 501, thestorage unit 201, to which other storage units can be connected throughthe FC interface units 235, sends volume information of the format 247shown in FIG. 10. The storage unit 101 and the storage unit 102 sendvolume information of the format 148 shown in FIG. 2 (B) and the format198 shown in FIG. 2 (C), respectively, to the management computer 501.As in the previous preferred embodiment described above, the managementcomputer 501 creates the consolidated information table 570 based on thevolume information and the hierarchy information thus collected. Indoing so, it relies on the lower volume flag shown in FIG. 10. Thelower-volume flag indicates the hierarchical relationship between thepair of volumes in its row with three values. The value of “0” meansthat there is no subordinate volume (i.e., the real volume is containedsolely in the first-level storage unit 201); the value of “1” means thatthe real volume is contained both the first-level storage unit and thesecond-level storage unit (i.e., they are synchronized by the datasynchronization control module 238); the value of “2” means that thereal volume is contained solely in the second-level storage unit. Thus,this embodiment is considered an expansion of the first preferredembodiment.

On the display 590 in the management computer 501, a screen 800 shown inFIG. 11 is displayed. The screen 800 has two display sections 801 and802 which are mutually exclusive. At any given time, either the displaysection 801 or the display section 802 is displayed. They are switchedalternately by a tab 811 and a tab 812: when the tab 811 is clicked, thedisplay section 801 appears on the screen 800; when the tab 812 isclicked, the display section 802 appears. Displayed in the displaysection 801 is the information in the column 571 of the consolidatedinformation table 570 as shown in FIG. 11 (A). The icon number in theconsolidated information table 570 is replaced with the real iconcorresponding to it.

Displayed in the display section 802 is the information in the column572 of the consolidated information table 570 as shown in FIG. 11 (B).The icon number in the consolidated information table 570 is replacedwith the real icon corresponding to it. It is also possible to add ahiding feature such that the tab 812, and hence the display section 802,is hidden from certain administrators registered in the managementcomputer. Such a feature can be used when certain administrators shouldbe made unaware of the hierarchical relationships between volumes.

Other ways of volume information display can also be envisaged. Forexample, by clicking an icon in the display section 801 it is possibleto check whether a subordinate volume exists. If a lookup of theconsolidated information table 570 indicates that a valid identifier isfound in the same row in the lower-volume column 572, then a subordinatewindow 820 appears on the display 590, displaying the information on thecorresponding subordinate volume, as shown in FIG. 12 (A).Alternatively, the information on the corresponding subordinate volumeis displayed in a separate display area 803 of the screen 800 as shownin FIG. 12 (B). In FIG. 12 (B), the two areas that are hierarchicallylinked are highlighted using shading. In a display area 804, the totaleffective capacity to the computers in the system is indicated.

A number of other variations of embodiments can also be envisioned. Forexample, whereas FIG. 4 assumed that the identifier management computer601 is independent of the management computer 501, these two computersmay also be consolidated in one computer, in which case the identifierformat request processing program 620 and the identifier format table650 are stored in the memory 513 in the management computer 501.

A number of embodiments of the present invention have been described.Nevertheless, it should be understood that various modifications may bemade without departing from the spirit and scope of the invention, andaccordingly that the invention is not limited by the specificillustrated embodiments but only by the scope of the appended claims.

1. In a computer system including a first storage apparatus having atleast one first volume and a second storage apparatus having at leastone second volume, a computer coupled to at least one of the first andsecond storage apparatus, wherein the first storage apparatus, thesecond storage apparatus, and the computer are coupled together viaFibre Channel interfaces, a management computer for managing capacity ofthe volumes in the computer system through a management network,comprising: a network interface arranged to be coupled to the managementnetwork; a processor coupled to the network interface; a memory coupledto the processor; and a display coupled to the processor; wherein theprocessor collects, via the network interface, capacity informationrepresenting the capacity of each first and second volume from the firstand second storage apparatus, respectively; the processor collects, viathe network interface, relationship information which definesrelationships between the first volumes and the second volumes, therelationship information including at least two of the following: firstrelationship information indicating a first volume that is a virtualvolume related to a second volume that is a data volume arranged tostore data for the computer and to be accessed by the computeraddressing the virtual first volume related thereto; second relationshipinformation indicating a first volume and a second volume that aresynchronized to store data for the computer with each other; and thirdrelationship information indicating a first virtual volume that is adata volume to store data for the computer and is unrelated to anysecond volume; the processor sums the capacity of the first and secondvolumes to obtain a total capacity of the volumes of the first andsecond storage apparatus; the processor subtracts from the totalcapacity, the capacity of any second volume indicated by the first orsecond relationship information; and the processor outputs the result ofthe subtraction to the display as the effective total capacity of thevolumes of the first and second storage apparatus.
 2. A managementcomputer according to claim 1, wherein the processor outputs, to thedisplay, a relationship between a first volume and a second volume withthe effective total capacity.
 3. In a computer system including a firststorage apparatus having at least one first volume and a second storageapparatus having at least one second volume, a computer coupled to atleast one of the first and second storage apparatus, wherein the firststorage apparatus, the second storage apparatus, and the computer arecoupled together via Fibre Channel interfaces, a management computer formanaging capacity of the volumes in the computer system through amanagement network, comprising: a network interface arranged to becoupled to the management network; a processor coupled to the networkinterface; a memory coupled to the processor; and a display coupled tothe processor; wherein the processor collects, via the networkinterface, capacity information representing the capacity of each firstand second volume from the first and second storage apparatus,respectively; the processor collects, via the network interface,relationship information which defines relationships between the firstvolumes and the second volumes, the relationship information includingfirst relationship information indicating a first volume that is avirtual volume related to a second volume that is a data volume arrangedto store data for the computer and to be accessed by the computeraddressing the virtual first volume related thereto, and secondrelationship information indicating a first virtual volume that is adata volume to store data for the computer and is unrelated to anysecond volume; the processor sums the capacity of the first and secondvolumes to obtain a total capacity of the volumes of the first andsecond storage apparatus; the processor subtracts from the totalcapacity, the capacity of any second volume indicated by the first orsecond relationship information; and the processor outputs the result ofthe subtraction to the display as the effective total capacity of thevolumes of the first and second storage apparatus.
 4. A managementcomputer according to claim 3, wherein the processor outputs, to thedisplay, a relationship between a first volume and a second volume withthe effective total capacity.
 5. A method for managing capacity ofvolumes in a computer system including a first storage apparatus havingat least one first volume and a second storage apparatus having at leastone second volume, and a computer coupled to at least one of the firstand second storage apparatus, wherein the first storage apparatus, thesecond storage apparatus, and the computer are coupled together viaFibre Channel interfaces, the method comprising the steps of: collectingcapacity information representing the capacity of each first and secondvolume from the first and second storage apparatus, respectively;collecting relationship information which defines relationships betweenthe first volumes and the second volumes, the relationship informationincluding at least two of the following: first relationship informationindicating a first volume that is a virtual volume related to a secondvolume that is a data volume arranged to store data for the computer andto be accessed by addressing the virtual first volume related thereto;second relationship information indicating a first volume and a secondvolume that are synchronized to store data with for the computer witheach other; and third relationship information indicating a firstvirtual volume that is a data volume to store data for the computer andis unrelated to any second volume; summing the capacity of the first andsecond volumes to obtain a total capacity of the volumes of the firstand second storage apparatus; subtracting from the total capacity, thecapacity of any second volume indicated by the first or secondrelationship information; and displaying the result of the subtractingstep as the effective total capacity of the volumes of the first andsecond storage apparatus.
 6. A method for managing capacity of volumesin a computer system according to claim 5, further comprising the stepof displaying a relationship between a first volume and a second volumewith the effective total capacity.